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Does additional air sealing improve performance linearly or exponentially?

hallie17 | Posted in Energy Efficiency and Durability on

I just had two energy audits done on my 1959 walk out ranch: one throgh the utility company’s program for $50 and one through an independent company for free. I wanted to see how the two compared so I could better advise my clients. The independant company was more enthusiastic about air sealing, but of course this also makes for a better sales pitch.

Part of their pitch was that if you seal just one area, the basement for instance, but don’t also address the attic and living areas, there is not nearly as much improvement in the home’s air sealing because the velocity of the air moving through the other openings will just increase. Is this true? Or will air infiltration decrease in direct proportion to the area of the openings in the envelope?

I had some air sealing done in the attic several years ago before adding insulation, but it wasn’t by a BPI certified contractor. Still, I’m a little reluctant to spend another $2,200 to improve the attic air sealing. I had hoped to focus my efforts on the rim joists.

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  1. GBA Editor
    Martin Holladay | | #1

    Additional air sealing will not provide "exponential" energy performance improvements.

    Any air sealing effort will improve energy performance, but the relationship between the air sealing and energy savings is complicated. Every house is unique. A house with huge single-paned windows and no insulation will see only a minor effect from air sealing, whereas a leaky house with triple-pane windows and lots of insulation will see a bigger effect.

  2. jklingel | | #2

    Also, you need to consider the structural savings by perhaps preventing moisture/rot problems, which could be enormous.

  3. hallie17 | | #3

    Thank you!

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